Hi Caridad,
In the meanwhile I updated to CRED 1.2.4 and the error you could reproduce isn't solved in this version:
Notice: Trying to get property of non-object in /www/web2738/www.caesarsbeauty.nl/http/wp-content/themes/toolset-bootstrap/theme-options/bootstrap-grid/grid-options.php on line 367 Notice: Trying to get property of non-object in /www/web2738/www.caesarsbeauty.nl/http/wp-content/themes/toolset-bootstrap/theme-options/bootstrap-grid/grid-options.php on line 368 Notice: Trying to get property of non-object in /www/web2738/www.caesarsbeauty.nl/http/wp-content/themes/toolset-bootstrap/theme-options/bootstrap-grid/grid-xml.php on line 287 Notice: Trying to get property of non-object in /www/web2738/www.caesarsbeauty.nl/http/wp-content/themes/toolset-bootstrap/theme-options/bootstrap-grid/grid-xml.php on line 288
About the other warning, you talk about the tablepress theme. In what way is tablepress a theme, is an plugin right? I do notice, that for example on the custom post type "Carousel items" the error also appears. It's true that this custom post type doens't have the 'editor' there. But when I go to edit the cred form, on that page are a lot of editors (for form content and notification settings), and there I also see buttons from other plugins show up, so why TablePress gives an error there is unclear for me.
You ask me, will you follow up with your theme author, but you are the theme author, because I use Toolset Bootstrap theme. Can you please clearify what you mean? Ofcourse I will do everything to get rid of the errors 
.